[Distraction osteogenesis for repair of cleft palate: an experimental study]

To observe the repair of cleft palate (CP) bone defect under the application of distraction osteogenesis (DO); to investigate the correction mechanism in thin bone of palatal shelf and to search a possible new treatment approach for repair of CP.

14 cats were assigned randomly to 3 groups: (1) Empty control, 2 cats unoperated with euthanasia at the end of 2 weeks; (2) Experimental control, 2 cats underwent 8 mm x 18 mm palatal osteoectomy in saggital direction as the experimental model of CP with euthanasia in 6 weeks; (3) Experimental group, 10 cats were performed the same palatal osteoectomy as group (2), the newly designed and individual manufactured intraoral distractors were fixed to teeth by brackets and to bilateral palate bone across the defect with titanium miniscrews. 4 weeks later the transport disc (TD) osteotomy were performed and gradual distraction was started after 6 days latency period at the rate of 0.4 mm x 2/day till the TD reached the opposite edge of the CP. Roentgenographic, gross meterage and ultrastructural observation were performed 2, 4, 6, 8, 12 weeks after completion of distraction.

All the examinations revealed the TD recombination to the opposite bone edge of the CP, simultaneously, the proportional expansion of overlay mucoperiosteal flap was achieved. The bone defect were filled with de move osteogenesis. Roentgenographically, the new bone mineralization was along the DO vector, developed from the bone cut edges bilaterally to the central translucent zone until turned to thin fissure. Comparison of the plaster casts showed no change in the occlusion or dentomaxillofacial framework.

The intraoral distractor is able to get both effective distraction and steady fixation. The examination results suggest that the CP bone and soft tissue defect could be repaired and acheived functional reconstruction under DO, which could be a new treatment approach for repair of CP.